In the link I posted, they take the green stuff off the top of the board to expose the shiny copper track below. That's "scraping the laminate off".thanks for the detailed reply.i'm not entirely sure what you meant by 'scraping the laminate off', though. i've never had a problem with a gray screen. it always consistently goes blank. sometimes, even after the boot chime. if so, there's sometimes hd activity, sometimes nothing. the fan never kicks in.
About the grey screen, I apologise, a blank screen is what I meant. It just happens that when the backlight shines onto the blank screen it looks a bit greyish.You could still give the burning method a shot, although the burning method shown in the link posted earlier is very different on an iBook G4 than it is on the G3, and the graphics chip is a lot harder to get to. You basically need to take the entire computer apart to get at it. On top of that I doubt that it would be the cause of the problem, considering the Vreg chip failure is the most common issue on these machines and it does sound like this is the problem in your case.
Another alternative of course is a new mainboard, and that could probably get the machine over the line for a few years.
The voltage regulator/vreg chip is the one that needs to be soldered back down, as I posted a link to earlier.
http://www.xlr8yourmac.com/tips/iBookG4_vreg_repair/ibookG4_vreg_repair.html
If you don't think you'll be able to take the solder repair path, there is a possibility you could shim the chip. Not the most elegant of solutions and not always the most reliable either, but if you want to keep it in mind as an option...
http://www.coreyarnold.org/ibook/
...then there's all the info you need to know about it. If that "shim fix" doesn't work though, the solder repair is the only other option short of replacing the entire board.